Genetic variability in a population of &lt;i&gt;Astyanax scabripinnis&lt;i&gt;: recent bottleneck and the possible influence of individuals with B chromosomes

Daniel Meneguello Limeira,Roberto Ferreira Artoni,Mara Cristina De Almeida,Mateus Henrique Santos,Rogério Pincela Mateus

doi:10.4025/actascibiolsci.v41i1.47323

Abstract

Access the genetic variability of endangered and isolated populations has become an important conservation tool. Astyanax scabripinnis is a well-known fish model for genetic studies, forming very isolated populations in headwaters. Besides that, this species frequently presents supernumerary chromosomes, which elevates the interest on genetic studies. Genetic diversity of an Astyanax scabripinnis population from the Atlantic Forest (Serra da Mantiqueira region, Brazil) was assessed with microsatellite markers for the first time. Since microsatellite markers are not described for this species, we tested markers described for a related species for transferability to A. scabripinnis. Six polymorphic loci were sufficiently reliable for population genetic analysis. We found that this population passed through a recent bottleneck because of the presence of an excess of heterozygotes, low allelic diversity, heterozygosity excess, and small effective population size. Individuals with and without B chromosomes were previously identified in this population and our study found private alleles in the individuals without B chromosomes. Furthermore, when individuals without B chromosomes were removed from the analysis, the population did not present heterozygosity excess, suggesting that the bottleneck event was driven by individuals with B chromosomes. Our results provide an insight into the value of microsatellite markers as molecular tools and is the first genetic study using molecular data of A. scabripinnis from this area.

Highlights

IntroductionThe Neotropical freshwater fish tetra, Astyanax scabripinnis (Jenyns, 1842), has become an important research subject in conservation genetics because of its ability to maintain small isolated but stable populations and its capacity for inhabiting heavily anthropized streams (Matoso, Artoni, & Galetti, 2004; Abilhoa, 2007; Abilhoa, Braga, Bornatowski, & Vitule, 2011)
The Neotropical freshwater fish tetra, Astyanax scabripinnis (Jenyns, 1842), has become an important research subject in conservation genetics because of its ability to maintain small isolated but stable populations and its capacity for inhabiting heavily anthropized streams (Matoso, Artoni, & Galetti, 2004; Abilhoa, 2007; Abilhoa, Braga, Bornatowski, & Vitule, 2011). Such small isolated populations are susceptible to losing genetic diversity, which reduces their ability to adapt to environmental variation (Westemeier et al, 1998)
Only six loci were used in the population studies, because they were shown to be more reliable for analyzing genetic variability in this species

Summary

Introduction

The Neotropical freshwater fish tetra, Astyanax scabripinnis (Jenyns, 1842), has become an important research subject in conservation genetics because of its ability to maintain small isolated but stable populations and its capacity for inhabiting heavily anthropized streams (Matoso, Artoni, & Galetti, 2004; Abilhoa, 2007; Abilhoa, Braga, Bornatowski, & Vitule, 2011). Such small isolated populations are susceptible to losing genetic diversity, which reduces their ability to adapt to environmental variation (Westemeier et al, 1998). It is likely that similar mechanisms may influence genetic diversity and population structure of A. scabripinnis

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Conclusion